The present invention relates generally to high security padlocks. More specifically, the present invention relates to high security padlocks used in locking two hasps or flanges together.
It is often desirable to lock two structures, such as two sliding vault doors together. For many situations, the use of a simple padlock having a shackle which is locked to adjacent hasps or flanges on the vault doors may be suitable for preventing opening of the vault doors; however, with the present availability of high power hydraulic and mechanical prying equipment in addition to the increased sophistication of criminals, this type of simple padlock proves many times inadequate and is not able to prevent prying open of vault doors.
As a result of the need to provide a suitable padlock for securely holding sliding vault doors or the like closed, there has been developed a typical padlock configuration which is especially useful for hold sliding doors or other surfaces together even when large prying or opening forces are applied to the doors.
In general, lock assemblies have now been developed in which the lock body itself holds the two sliding doors together. The lock body is made of stainless steel and includes retaining surfaces which define a U-shaped opening for receiving hasps or flanges mounted on the sliding vault doors. When the vault doors are closed, the flanges are typically adjacent each other. By placing the lock body on the flanges, the retaining arms are moved into place to prevent opening of the vault doors. In this manner, a lock body made of stainless steel and having heavy weight construction is utilized to provide a much stronger lock to prevent vault door opening.
In order to prevent the lock body from being removed from its retaining position about the flanges, a latch bolt or other similar locking mechanism is utilized to attach the lock body securily to the flanges to prevent removal.
Even though this type of high strength lock assembly serves its purpose to prevent prying open of vault doors or other support structures, the increasing sophistication of criminals has resulted in the need for providing tamper proof features to the above-described lock configuration. For example, since the latch bolt which holds the lock body in place on the flanges is typically weaker than the flange retaining arms, a common practice is to saw through, drill or otherwise destroy the latch bolt to allow removal of the lock body from the flanges. It would therefore be desirable to provide the above-described padlock device with some type of shield to prevent external access to the latch bolt.
Another method used by criminals for tampering with high security locks involves the use of acids. Usually, the locking or stress elements of a lock are made from hard strong materials, such as stainless steel. Although stainless steel is subject to attack and corrosion by many acids, stainless steel is generally much more acid resistant than copper alloys, such as brass and bronze which are commonly used for lock cylinders. Therefore, acids are being used increasingly to attack the non-acid resistant lock cylinder. Once the lock cylinder has been destroyed by chemical action, the latch bolt can then be manipulated away from its engagement with the flanges to allow removal of the lock body from its old retaining position about the flanges. It is therefore apparent that there is a present need to provide a safety relock mechanism to lock the latchbolt in its locked position upon attack and destruction of the lock cylinder by acid.
A further area in which criminals have successfully tampered with padlocks involves the removal of the lock cylinder entirely from the lock body. Typically, the lock cylinder is held in place within the lock body by a lock cylinder housing. The lock cylinder housing is fastened to the lock body in such a way that unfastening of the screws or bolts can only be accomplished when internal access is gained to the lock body. This problem is especially important in the above-described retaining type padlocks because access to the fastening screw or bolt is typically provided by way of the flange receiving opening. Therefore, if the flange receiving opening is inadequately covered or if access is otherwise gained to the flange receiving opening, the lock cylinder housing and lock cylinder would be easily removable. It would be desirable to provide some type of key acutated locking mechanim to lock the lock cylinder housing in place, regardless of other fastening means used, to prevent removal of the lock cylinder accept upon the specific keyed actuation.